99 NZMJ 25 October 2019, Vol 132 No 1504ISSN 1175-8716 © NZMAwww.nzma.org.nz/journal

Erysipelothrix rhusiopathiae bacteraemia in an immunocompromised

host: the unexpected complication of a

crustacean altercationEben Jones, Peter Burrell, Tony Barnett, David Lyons-Ewing,

Elisabeth Nuttall

Zoonotic infections are infrequently considered and subsequently un-der-diagnosed. Here we report a case

of Erysipelothrix rhusiopathiae infection as a means of highlighting the importance of both considering and investigating for zoo-notic infections in patients presenting with infective symptoms.

Case reportA retired 57-year-old man presented to

Nelson Hospital with a three-day history of fevers, nausea, headaches, myalgia and

lethargy. History revealed no localising symptoms of infection, and he reported no recent foreign travel. His past medical history included psoriatic arthritis and diabetes mellitus. His medications included prednisone, methotrexate and etanercept.

On examination, his temperature was 35.7oC, blood pressure was 80/60mmHg, and he was noted to have a 5x7cm, purple, crusted lesion on the dorsum of his left wrist (Figure 1). The lesion was not cellulitic. The patient had no murmur or peripheral stigmata of infective endocarditis.

Figure 1: Skin lesion on the patient’s wrist.

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The working diagnosis of sepsis of unknown source with associated adrenal insuffi ciency was treated with 4L of IV crystalloid, IV ceftriaxone and IV hydrocortisone.

Following 20 hours of incubation the anaerobic blood cultures were reported to be growing fi ne Gram-negative bacilli (Figure 2). Two days later, the organism was identifi ed as E. rhusiopathiae by MALDI-TOF mass spectrometry.

Table 1: Initial investigations.

Admission value Reference ranges

Haematology

Haemoglobin 144 130–175g/L

White cell count 13.2 4.0–11.0x109/L

Neutrophil count 11.5 1.9–7.5x109/L

Lymphocyte count 0.6 1.0–4.0x109/L

Biochemistry

Sodium 136 135–145mmol/L

Potassium 5.7 3.5–5.2mmol/L

Lactate 2.73 0.5–1.6mmol/L

CRP 124 0-5mg/L

Imaging

Chest x-ray No focal consolidation

Microbiology

Blood cultures Sent prior to the administration of antibiotics

Urine microscopy Leucocytes: 21–50x10^6/L Red cells: <10x10^6/L

Figure 2: An example of the Gram-variable nature of E. rhusiopathiae.1

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Figure 3: The culprit crustacean.

Further questioning revealed that the patient had suffered small puncture wounds to his left wrist while handling salt-water crayfi sh in Kaikoura fi ve days prior to the onset of symptoms (Figure 3). His family also kept sheep and chickens, but he denied recent contact with these animals.

Considering this bacterium’s association with infective endocarditis, a trans-thoracic echocardiogram was performed, which demonstrated no vegetations. Due to the patient’s rapid clinical recovery, subse-quent negative blood cultures and lack of stigmata of endocarditis, a trans-oesoph-ageal echocardiogram was not performed. The antibiotic regimen was rationalised to a seven-day course of oral amoxicillin. At follow-up, the patient was asymptomatic and felt that he had made a full recovery.

DiscussionErysipelothrix rhusiopathiae is a facul-

tatively anaerobic non-spore-forming Gram-positive bacillus. It has Greek etymology, and combines the terms erythros (red), pella (skin) and thrix (thread-like). It was fi rst isolated by Robert Koch in 1876, and is recognised as a zoonotic pathogen in humans.2

E. rhusiopathiae is hosted by a range of wild and domesticated mammals, birds, amphibians and marine species, including crayfi sh.3 Human infection is associated with occupational and recreational expo-sures to animals and their excretions, with case reports clustered among farmers, butchers and fi sh-handlers.4–6 In this case, the likely source of infection was a puncture wound sustained while handing a salt-water crayfi sh. This case underlines the impor-tance of considering zoonotic exposures when confronted with a septic patient with no clear source.

Human disease most commonly presents as a well-defi ned violaceous lesion (erysip-eloid) that normally resolves without treatment.7 E. rhusiopathiae bacteraemia is substantially rarer, but commonly results in a severe clinical illness, associated with endocarditis in over one-third of cases.8 Specifi c risk factors for systemic illness in this case included diabetes mellitus and immunosuppression. Additionally, a variety of focal disease has been rarely reported, including central nervous system infection, osteomyelitis, septic arthritis, liver abscess and intra-abdominal abscess.9

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Competing interests:Nil.

Author information:Eben Jones, Registrar, Department of General Medicine, Nelson Hospital; Honorary Clinical

Lecturer, University of Otago; Peter Burrell, House Offi cer, Department of General Medicine, Nelson Hospital; Tony Barnett, Head Microbiologist, Medlab South;

David Lyons-Ewing, Registrar, Department of General Medicine, Nelson Hospital; Honorary Clinical Lecturer, University of Otago; Elisabeth Nuttall, Registrar, Department of General

Medicine, Nelson Hospital; Honorary Clinical Lecturer, University of Otago.Corresponding author:

Dr Eben Jones, General Medicine Nelson Marlborough District Health Board.ebenjones90@gmail.com

URL:http://www.nzma.org.nz/journal/read-the-journal/all-issues/2010-2019/2019/vol-132-no-1504-

25-october-2019/8029

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2. Brooke CJ, Riley TV. Erysip-elothrix rhusiopathiae: bacteriology, epidemiology and clinical manifesta-tions of an occupational pathogen. J Med Microbiol. 1999 Sep; 48(9):789–99.

3. Fidalgo SG, Wang Q, Riley TV. Comparison of Methods for Detection of Erysipelothrix spp. and Their Distribution in Some Australasian Seafoods. Appl Environ Microbiol. 2000 May;66(5):2066–2070.

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opathiae septicemia. Scand J Infect Dis. 1985; 17(1):123–4.

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6. Robson JM, McDougall R, van der Valk S, et al. Erysipelothrix rhusiopathi-ae: An uncommon but ever present zoonosis. Patholo-gy. 1998 Nov; 30(4):391–4.

7. R eboli AC, Farrar WE. Erysipelothrix rhusi-opathiae: an occupational pathogen. Clin Microbiol Rev. 1989 Oct; 2(4):354–9.

8. Principe L, Bracco S, Mauri C, et al. Erysipelothrix rhusiopathiae Bacteremia

without Endocarditis: Rapid Identifi cation from Positive Blood Culture by MALDI-TOF Mass Spectrometry. A Case Report and Literature Review. Infect Dis Rep. 2016 Mar 21; 8(1):6368.

9. Erysipelothrix rhusiopathi-ae. Annette C, Reboli MD. antimicrobe.org [Internet]. E-Sun Technologies, Inc. 2010-2014. Cited 2019 Apr 7. Available from: http://www.antimicrobe.org/new/b76.asp

10. Bratcher DF. In: Long SS, editor. Principles and Practice of Pediatric Infectious Diseases. 4th ed. Amsterdam: Elsevi-er; 2012, p767–771.

This case serves to illustrate the potential for opportunistic zoonotic infections in immunocompromised individuals, and some of the pitfalls experienced when diagnosing human disease caused by E. rhusiopathiae. Gram-stain may yield a Gram-variable result due to poor retention of the stain.10 Indeed, the provisional report

in this instance was of a Gram-negative organism. Secondly, since many Gram-pos-itive bacilli that grow in blood cultures represent sample contamination, some labs may not proceed to fully characterise these organisms. Combined, these factors may contribute to delayed or under-diagnosis of this clinically signifi cant organism.

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